Safety plug-in electrical receptacle



Aug. 10, 1948. H. F. WlTTlG SAFETY PLUG-IN ELECTRICAL RECEPTACLE 2 Sheets-Sheet 1 Filed March 29, 1945 T 0 f N E U H I Aug. 10, 1948. H. F. WITTIG SAFETY PLUG-IN ELECTRICAL RECEPTACLE 2 Sheets-Sheet 2 Filed March 29, 1945 Patented Aug. 10, 1948 SAFETY PLUG-IN ELECTRICAL RECEPTACLE Homer F. Wittig, Green Bay, Wla, assignor of one-half to Diedrich J. Wittig, Green Bay,

Application March 29, 1945, Serial No. 585,489 1 Claim. (01. 173-330) This invention relates to an improved electrical receptacle, and one of its objects is to provide an electrical receptacle and a plug-in connector, with means for locking the plug-in connector in circuit connecting position against disengagement by a direct pull upon the cord of the connector, or the plug-in connector itself, but which will permit of easy manual separation by a slight turning movement of the plug-in connector.

Another object of the invention is to provide a safety electrical receptacle with contact spring elements, and with plug-in prong receiving slots, so arranged that the connecting circuit wires cannot be shorted by a child or other person inserting metal wires or pins through the slots.

With the above and other objects in view the invention consists in certain new and useful constructions, combinations, and arrangements of parts, clearly described in the following specification, and fully illustrated in the accompanying drawings, in which:

Fig. 1 is a front elevation of the improved safety receptacle, with the socket plate in position.

Fig. 2 is an enlarged front elevation of the receptacle, showing the front plate removed, the socket or prong receiving openings being indicated in dotted lines.

Fig. 3 is a view of Figure 2, partly in section.

Fig. 4 is a transverse sectional view, taken on line 4-4 of Fig. 2, looking in the direction of the arrows.

Fig. 5 is a detail side view of a plug-in connector.

Fig. 6 is a detail end view thereof.

Referring to the accompanying drawings, which illustrate the practical construction of my invention, 5 designates a base block of refractory material or of other insulating material, on which is mounted the intermediate contact spring element 6, which is provided with outwardly disposed yielding spring arms 1 and 8, which extend on opposite sides of the connecting screw '9, by which the contact spring element 6 is electrically connected to the conductor bar l0, which carries a circuit wire connecting screw H thereon.

The spring arm 1 is curved around the axis of the connector prong receiving opening l2 and I3, formed in the frontal plate l4, which is attached to the insulating block 5 by means of the central holding screw l5. A boss of insulating material separates the spring contact element 6 from the holding screw 15. The opening I2 is arcuate along its entire inner edge and is arcuate for the major portion of its outer edge and is then enlarged at Ma to provide a key receiving ofl'set opening. The opening i3 is simi-v larly constructed, being provided on one end with a key receiving offset opening I 3a. These key receiving oil'set openings are located in opposition to each other.

The spring arm 8 is similarly curved about the center of the arcuate slots l6 and I1, formed in the front plate I4, and these slots are of similar construction to the slots 12 and I3. .The slot I6 is formed with a key receiving ofiset opening lid and the slot I1 is formed with a key receiving oflset opening Ila, which is located in opposition to the opening lfia.

The curved spring arm 1 is disposed in concentric relation to the prong receiving slots I2 and I3, and the curved spring arm 8 is disposed in concentric relation to the prong receiving slots l6 and I1, and the slots are located inwardly of the circular planes of the spring arms.

A single spring contact arm I8 is attached to the base block 5 in concentric relation to the slot l3, and adjacent to it, but located outwardly of this slot, by means of the connector screw I9. A single spring contact arm 20 is attached to the base block 5, adjacent and concentric to the slot l1, and outwardly thereof, by means of the connector screw 2|. The contact arm [8 is connected to the binding or circuit connecting screw 22 by means of the conductor spring piece 23, and the contact arm 20 is connected to this binding screw by means of the conductor strip 24.

The intermediate spring contact element 6 is the positive element and the contact spring arms l8 and 20 are the negative elements.

The plug-in connector consisting of a body 25, which may be conical as shown, and which is provided with conductor prongs 26 and 21. The prong 26 is attached to the body of the plug by means of the base wing 26a and the holding or binding screw 28, and the prong 21 is attached to the body of the plug by means of its wing 21a and the holdingor binding screw 29. The prong 26 is formed with a lateral key 26b on its outer end, and the prong 2'! is formed with a lateral key 21b on its outer end, which project in opposite directions from each other, so as to provide a normal gap between the prongs.

plate, or case, so that the keys of the two prongs will be in registration with the key ofiset openings or the slots, and then the plug is turned so that the keys of the prongs will ride or move against the plate and be out of registration with the offset key openings of these slots. When this takes place the prongs will bear against the spring contact arms, thereby bridging these contacts,

and closing the circuit through the electrical unit with which the wires of the plug-in connector are connected in circuit, provided of course that any external switch is closed.

Contact between the prongs of the plug-in When the plug-in connector has been properly 7 connected with the spring arms of the receptacle, the prong keys will resist a direct pull upon the plug or its connecting wires or cord, and release will require a manual unlocking turning movement of the plug on the receptacle. This prevents the accldental pulling out of the connecting plug, and compels the user to go to the receptacle and properly disengage or uncouple the plug.

Should any one insert a hair pin or a wire through one or both slots the spring arms adjacent the slots will not be engaged, and the circuit will not be shorted.

Having described my invention it is understood that various changes in the proportions, construction and combination of parts, may beresorted to. within the scope of the claim of this application.

Having described my invention I claim as new:

An electrical conductor coupling comprising an elongated rectangular base of non-conducting material, a contact spring fixed midway between opposite ends of the base, opposite ends of the spring curving away from the base and terminating in arcuate contacts which extend toward adjacent ends of the base adjacent opposite sides thereof, s'aid arcuate contacts lying in spaced relation to the base, a conductor strip lying,a1ong one side of the base, spring contact members at opposite ends of the conductor strip, an arcuate contact on each spring contact memher, said last-named arcuate contacts being spaced from the base for cooperating with the contacts carried by the spring to provide a pair of spaced arcuate contacts adjacent each end of the base, a cover for said base, said cover having a pair of arcuate slots lying concentric with and inside the inner edges of each pair oi! arcuate contacts, a plug connector carrying spaced contacts adapted to enter a pair of arcuate slots in the cover, laterally extendin ears on the contacts of the plug connector adapted upon rotation of the plug to engage the arcuate contacts, stops at the free ends of the arcuate contacts to engage the ears and arrest rotation of the plug when the ears are in full contact with the arcuate contacts and the cover having a notch opening into each arcuate slot to accommodate the ear on a plug contact.

HOMER F. WITTIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,294,444 Goetzelman Feb. 18, 1919 1,618,939 Marth Feb. 22, 1927 2,043,247 Hubbell June 9, 1936 2,060,887 Navert Nov. 17, 1936 2,312,017 Ackerman Feb. 23, 1943 

